Temp log
Frozen storage −18°C or colderChilled foods 0 to 5°C typicalBananas avoid below ~13°CDanger zone 5–60°CIce cream hardening −25°C to −30°CLeafy greens 0–2°C, high humidityChocolate around 15–18°C, dryLive seafood species-specificBlast freezer air −30°C to −40°CCured vanilla cool, dry, sealedFrozen storage −18°C or colderChilled foods 0 to 5°C typicalBananas avoid below ~13°CDanger zone 5–60°CIce cream hardening −25°C to −30°CLeafy greens 0–2°C, high humidityChocolate around 15–18°C, dryLive seafood species-specificBlast freezer air −30°C to −40°CCured vanilla cool, dry, sealed

Cold Chain

Natural refrigerants in food processing and retail refrigeration: the 2026 state of play

CO2, ammonia and propane are moving from niche to normal as high-GWP HFCs are phased down. Each suits different sites, and each brings its own safety and skills questions.

By Editorial desk · · 3 min read

CO2 (R744)
GWP 1; high pressures; strong in supermarkets
Ammonia (R717)
GWP 0; toxic; long-standing in large industrial plants
Propane (R290)
GWP about 3; flammable; common in self-contained cases

Food processing and retail refrigeration are going through a long change of refrigerants. Hydrofluorocarbons (HFCs), which replaced ozone-depleting gases, have high global warming potential (GWP). International agreements, including the Kigali Amendment to the Montreal Protocol, and regional rules such as the European Union's revised F-gas Regulation, are phasing them down. US rules under the AIM Act are also restricting high-GWP HFCs in new equipment.

Natural refrigerants, mainly carbon dioxide, ammonia and hydrocarbons such as propane, are taking their place. Here is where things stand in 2026.

Carbon dioxide (R744)

CO2 has a GWP of 1. It is non-flammable and has low toxicity at the concentrations typical of leaks, though high concentrations in enclosed spaces are dangerous. It works at much higher pressures than HFC systems.

Where it is used: supermarket refrigeration, especially transcritical CO2 "booster" systems that serve both chilled and frozen cases. It is also used in cold stores, food processing and some heat pumps.

State of play: transcritical CO2 has become a standard choice for new supermarkets in Europe and is spreading in North America and parts of Asia. Earlier concerns about efficiency in hot climates have been reduced by technologies such as parallel compression and ejectors. Heat recovery from CO2 systems can supply hot water and space heating.

Challenges: high-pressure components, technician training and higher upfront cost in some markets.

Ammonia (R717)

Ammonia has a GWP of zero and excellent thermodynamic properties. It has been used in industrial refrigeration for more than a century. It is toxic and, at certain concentrations, flammable, so systems require strict safety measures.

Where it is used: large cold stores, meat and dairy processing, breweries, frozen food plants and distribution centres.

State of play: ammonia remains the main choice for large industrial plants. The trend is toward low-charge ammonia systems, which reduce the amount of ammonia on site, and ammonia/CO2 cascade systems, where ammonia stays in a machine room and CO2 circulates to the cold areas.

Challenges: safety regulations, specialist skills and the need to keep ammonia away from occupied spaces.

Propane and other hydrocarbons (R290, R600a, R1270)

Propane has a very low GWP (around 3). It is efficient but highly flammable, so charge sizes are limited.

Where it is used: self-contained (plug-in) display cases, bottle coolers, ice-cream freezers, small commercial units and some chillers. Isobutane (R600a) is common in domestic refrigerators.

State of play: updated international safety standards have allowed larger hydrocarbon charges in commercial appliances, which has expanded their use. Some retailers now use water-loop systems, where many propane cabinets reject heat into a shared water circuit.

Challenges: flammability, safe handling and limits on charge size.

HFOs and blends

Hydrofluoroolefins (HFOs) and HFO blends offer lower GWP than HFCs and are used in some retrofit and new systems. They are not "natural" refrigerants, and their breakdown products, including concerns linked to PFAS rules in some regions, are under scrutiny.

Retrofit or replace?

Many food sites still run HFC systems with years of life left. Operators face a choice between retrofitting with a lower-GWP drop-in, running existing equipment to the end of its life while managing leaks closely, or replacing it with a natural refrigerant system. The answer depends on the age of the plant, how much it leaks, how easy it is to get the refrigerant, and future service bans in the jurisdiction. A phased plan, starting with the leakiest or oldest systems, is often the most practical route. Leak detection and good maintenance pay off whatever the refrigerant.

What operators should consider

  1. Site size and type: ammonia for large industrial plants, CO2 for supermarkets and medium sites, hydrocarbons for plug-in equipment.
  2. Climate: hot climates may need more advanced CO2 designs.
  3. Skills: technicians need training for high pressure, toxicity or flammability.
  4. Lifecycle cost: energy use, maintenance and future regulatory risk.
  5. Heat recovery: using waste heat can improve the business case.

The shift to natural refrigerants is no longer experimental. The questions now are about design, skills and getting the right system for each site.

Key figures above are general reference points, not regulatory limits.